A wide variety of foldable plastic chairs have been designed which allow a chair to be unfolded and the seat lowered to a horizontal position for use, and allow the seat to then be raised and the chair collapsed into a folded position following usage. For safety reasons, it is important that the chair, when in its unfolded seating position, be able to withstand the substantial dynamic loads associated with persons sitting on the seat of the chair, without the seat folding or being broken.
More particularly, such chairs are often used in offices, and in this regard it is desirable that such chairs meet the American National Standard for Office Furnishings criteria as set out in ANSI/BIFMA X5.1-1985. Since these standards have been revised fairly recently, many previous chair designs do not meet these standards. It is desirable to provide a foldable plastic chair which is lightweight, comprised of a minimal number of components, easily moved between extended and folded positions without any special knowledge of the chair's operation, lends itself to low cost production and yet still meets the safety criteria set out in the aforementioned ANSI standards.